[CIFS] Fix mtime on cp -p when file data cached but written out too late

Kukks noticed that cp -p can write out file data too late, after the timestamp
is already set.  This was introduced as an unintentional sideeffect of the change
in an earlier patch (see below) which fixed some delayed return code propagation.

cea218054ad277d6c126890213afde07b4eb1602
Author: Jeff Layton <jlayton@redhat.com>
Date:   Tue Nov 20 23:19:03 2007 +0000

Acked-by: Shirish Pargaonkar <shirishp@us.ibm.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/inode.c

@@ -1420,11 +1420,10 @@ int cifs_setattr(struct dentry *direntry, struct iattr *attrs)
 	}
 	cifsInode = CIFS_I(direntry->d_inode);
 
-	/* BB check if we need to refresh inode from server now ? BB */
-
-	if (attrs->ia_valid & ATTR_SIZE) {
+	if ((attrs->ia_valid & ATTR_MTIME) || (attrs->ia_valid & ATTR_SIZE)) {
 		/*
-		   Flush data before changing file size on server. If the
+		   Flush data before changing file size or changing the last
+		   write time of the file on the server. If the
 		   flush returns error, store it to report later and continue.
 		   BB: This should be smarter. Why bother flushing pages that
 		   will be truncated anyway? Also, should we error out here if
@@ -1435,7 +1434,9 @@ int cifs_setattr(struct dentry *direntry, struct iattr *attrs)
 			CIFS_I(direntry->d_inode)->write_behind_rc = rc;
 			rc = 0;
 		}
+	}
 
+	if (attrs->ia_valid & ATTR_SIZE) {
 		/* To avoid spurious oplock breaks from server, in the case of
 		   inodes that we already have open, avoid doing path based
 		   setting of file size if we can do it by handle.